The influence of intense ballet training on trabecular bone mass, hormone status, and gonadotropin structure in young women

Evaluation of Trabecular Bone Microarchitecture and Bone Mineral Density in Young Women, Including Selected Hormonal Parameters

The absence of non-invasive methods for assessing bone material and structural changes is a significant diagnostic challenge. Dual-energy X-ray absorptiometry (DXA) bone mineral density (BMD) testing is the gold standard for osteoporosis diagnosis. BMD and the trabecular bone score (TBS) have facilitated targeted osteoporosis prevention and treatment in clinical settings. The findings from this study indicate that BMD modulation in young women is influenced by various hormones, potentially compromising the diagnostic precision of BMD for subclinical bone demineralization. A total of 205 women aged 19 to 37 underwent anthropometric measurements and hormonal tests. BMD was determined using DXA, and TBS values were computed from the lumbar spine L1-L4 segment. The multivariate analysis findings suggest that BMD might not be determined by hormones. The relationship between TBS and TSH was statistically significant in the univariate analysis, which indicates the efficacy of further studies to determine the link between TBS and specific hormones. Analyzing the strength of the correlation between TBS and hormones in the univariate analysis shows which factors are worth considering in further analyses. This makes it possible to create better techniques that will help identify young women who are at a higher risk of developing osteoporosis.

Effects of the Type of Exercise Training on Bone Health Parameters in Adolescent Girls: A Systematic Review

Interventional studies offer strong evidence for exercise's osteogenic impact on bone particularly during growth. With rising osteoporosis rates in older women, enhancing bone strength early in life is crucial. Thus, investigating the osteogenic effects of different types of physical activities in young females is crucial. Despite varied findings, only two systematic reviews tried to explore this topic without examining how different types of exercise may affect bone health in adolescent girls. The first aim of this systematic review was to assess the impact of exercise training on bone health parameters in adolescent girls, and the second aim was to investigate whether the type of exercise training can modulate this effect. A systematic literature search was conducted using common electronic databases from inception - January 2023. Seven studies (355 participants) were eligible for inclusion in this systematic review. Two studies dealt with resistance training, 3 studies applied plyometric training, 1 study used team sports, and 1 study used dancing. Results indicate that plyometric training increases lumbar spine bone mass in adolescent girls. Well-designed randomized controlled trials with a proper training period (> 12 weeks) are needed to advocate a specific type of training which has the highest osteogenic effect.

Bone health in functional hypothalamic amenorrhea: What the endocrinologist needs to know

In the original definition by Klinefelter, Albright and Griswold, the expression "hypothalamic hypoestrogenism" was used to describe functional hypothalamic amenorrhoea (FHA). Given the well-known effects of estrogens on bone, the physiopathology of skeletal fragility in this condition may appear self-explanatory. Actually, a growing body of evidence has clarified that estrogens are only part of the story. FHA occurs in eating disorders, overtraining, and during psychological or physical stress. Despite some specific characteristics which differentiate these conditions, relative energy deficiency is a common trigger that initiates the metabolic and endocrine derangements contributing to bone loss. Conversely, data on the impact of amenorrhoea on bone density or microarchitecture are controversial, and reduced bone mass is observed even in patients with preserved menstrual cycle. Consistently, oral estrogen-progestin combinations have not proven beneficial on bone density of amenorrheic women. Low bone density is a highly prevalent finding in these patients and entails an increased risk of stress or fragility fractures, and failure to achieve peak bone mass and target height in young girls. Pharmacological treatments have been studied, including androgens, insulin-like growth factor-1, bisphosphonates, denosumab, teriparatide, leptin, but none of them is currently approved for use in FHA. A timely screening for bone complications and a multidisciplinary, customized approach aiming to restore energy balance, ensure adequate protein, calcium and vitamin D intake, and reverse the detrimental metabolic-endocrine changes typical of this condition, should be the preferred approach until further studies are available.

Associations between nutrition, energy expenditure and energy availability with bone mass acquisition in dance students: a 3-year longitudinal study

Three years of study showed that female and male vocational dancers displayed lower bone mass compared to controls, at forearm, lumbar spine and femoral neck. Energy intake was found to positively predict bone mass accruals only in female dancers at femoral neck. Vocational dancers can be a risk population to develop osteoporosis.

PURPOSE

To determine whether risk factors normally associated with low bone mass in athletic populations (i.e. nutrition intake, energy expenditure and energy availability) are significant predictors of bone mass changes in vocational dance students.

METHODS

The total of 101 vocational dancers (63 females, 12.8 ± 2.2 years; 38 males, 12.7 ± 2.2 years) and 115 age-matched controls (68 females, 13.0 ± 2.1 years; 47 males, 13.0 ± 1.8 years) were monitored for 3 consecutive years. Bone mass parameters were measured annually at impact sites (femoral neck, FN; lumber spine, LS) and non-impact site (forearm) using DXA. Nutrition (3-day record), energy expenditure (accelerometer), energy availability and IGF-1 serum concentration (immunoradiometric assays) were also assessed.

RESULTS

Female and male vocational dancers had consistently reduced bone mass at all anatomical sites (p < 0.001) than controls. IGF-1 did not differ between male vocational dancers and controls, but female dancers showed it higher than controls. At baseline, calcium intake was significantly greater in female vocational dancers than controls (p < 0.05). Male vocational dancers' fat and carbohydrate intakes were significantly lower than matched controls (p < 0.001 and p < 0.05, respectively). Energy availability of both female and male vocational dancers was within the normal range. A significant group effect was found at the FN regarding energy intake (p < 0.05) in female dancers. No significant predictors were found to explain bone mass differences in males.

CONCLUSION

Our 3-year study revealed that both female and male vocational dancers displayed lower bone mass compared to controls, at both impact and non-impact sites. The aetiology of these findings may be grounded on factors different than those usually considered in athletic populations.

Body composition and eating behaviour in non-professional adolescent female dancers

BACKGROUND

Dance is one of the most practiced sports in women's childhood and adolescence. It is often difficult for dancers to maintain a normal body composition without changing their eating habits, despite the presence of high intensity training. The study aims to investigate, through nutritional habits and body composition, the impact of this sports regime in the prepubertal period.

METHODS

Two groups of 10 adolescent dancers of classic and modern style were evaluated in terms of anthropometric parameters and hydration. Lifestyle, eating habits, adherence to Mediterranean diet, characteristics of menstrual cycle and risk stratification of Athletes' Triad Syndrome were evaluated through questionnaires. The data were reinterpreted based on the presence or absence of menarche.

RESULTS

The average BMI value was within the normal range (17.9 ± 2.2 kg/m2) in both groups. No significant differences emerged for anthropometric parameters and body composition between the two groups with the exclusion of the suprailiac fold which was significantly lower in G2 (classical: 0.1 ± 0.1 mm) compared to G1 (modern: 11.0 ± 6.6 mm) p < 0.001. Instead, differences observed (p < 0.05) was related to the presence or absence of the menstrual cycle. Despite the poor adherence to the Mediterranean diet, there was no evidence of risk of developing eating disorders or Athletes' Triad Syndrome.

CONCLUSIONS

The training of classical and modern dance does not seem to have any negative impact on the body composition especially in pre-pubertal age. The onset of the menarche determines the major modification of the body composition.

Early menarche and its consequence in Korean female: reducing fructose intake could be one solution

The mean age at menarche (AAM) of Korean females has been rapidly decreasing over the last 50 years; currently, the prevalence of early menarche (<12 years) is 22.3%. Female adolescents who experience early menarche are known to be at greater risk of psychosocial and behavioral problems along with several physical health problems such as menstrual problems. They also tend to achieve a shorter final height and develop obesity. Population-based Korean studies have shown a strong association between early menarche and the risk of obesity, insulin resistance, metabolic syndrome, nonalcoholic fatty liver disease, diabetes, breast cancer, and cardiovascular disease in adulthood. Although the exact mechanism of how early menarche causes cardiometabolic derangement in later adulthood is unknown, childhood obesity and insulin resistance might be major contributors. Recent studies demonstrated that an excessive consumption of fructose might underlie the development of obesity and insulin resistance along with an earlier AAM. A positive association was observed between sugar-sweetened beverages (a major source of fructose) intake and obesity, metabolic syndrome, insulin resistance, and cardiometabolic risk in Korean females. In pediatrics, establishing risk factors is important in preventing disease in later life. In this regard, early menarche is a simple and good marker for the management of cardiometabolic diseases in adulthood. Decreasing one's fructose intake might prevent early menarche as well as the development of obesity, insulin resistance, and cardiometabolic diseases.

Special Considerations for Growing Dancers

Care of young dancers requires a unique approach during a critical time of growth and development. Young dancers' well-being depends on factors including sleep, mental health, growth-associated musculoskeletal imbalances, and nutrition. Puberty is a particularly important time for young dancers. It coincides with an increased commitment to their art form and physical/psychosocial changes. It is imperative for practitioners to understand these various factors in order to optimize young dancers' health and allow them to safely train and perform.

Bone mineral density in adolescent elite ballet dancers

BACKGROUND

Data documenting BMD in pre-professional adolescent ballet dancers is limited. This cross-sectional study assesses bone mineral density (BMD) in young adolescent elite ballet dancers and compares BMD values between males and females (with and without normal menarche) and body composition between dancers with and without low Z-score.

METHODS

Cross-sectional study of third year ballet students (female=23; male=15; mean age 14.7 years; SD: 0.5) of The Royal Ballet School of Antwerp (Belgium) training 22 hours a week. They completed questionnaires and underwent dual energy X-ray absorptiometry (DXA) to measure BMD and body composition. Each female participant completed questionnaires assessing menstrual status.

RESULTS

DXA revealed that 12 out of 38 (32%) of the dancers had Z-score <-1. On average, male dancers had a lower BMD compared to an age-matched reference population (mean Z-score -0.9; SD 0.5), with 7 out of 15 having Z-score <-1. Overall, absolute BMD values were highest in the legs, followed by spine and arms. Dancers with Z-score <-1 had a significantly lower total mass. 43% of female ballet dancers had not yet had their first period and 39% had oligomenorrhea, but no significant differences between groups was detected.

CONCLUSIONS

A third of adolescent elite ballet dancers had low to very low Z-score. Nearly 2 out of 3 dancers with a Z-score <-1 were males, showing that low BMD is not limited to female dancers. Among female dancers menstrual dysfunction was frequent, without apparent impact on BMD or body composition in the studied age group.

Systematic review and meta-analysis of the association between childhood physical activity and age at menarche

AIM

To systematically appraise and summarise published evidence on the association between childhood physical activity (PA) and subsequent age at menarche (AAM).

METHODS

We searched PubMed (1990-2018) for studies that reported the relationship between childhood PA and AAM. We performed tabular synthesis of population-based studies and a random-effects meta-analysis of results of athlete/nonathlete studies.

RESULTS

One randomised controlled trial was identified, in which an intervention to prevent obesity reduced the likelihood of menarche during the two-year study period (relative risk: 0.75, 95% CI: 0.66-0.87; n = 422 girls). One of five prospective cohort studies (total n = 4492) reported a significant association between self-reported PA duration and subsequent menarche timing. Four of five historical cohort studies (total n = 89 470) reported significant associations between recalled premenarcheal PA and later AAM. Meta-analysis across 12 athlete/nonathlete studies showed that menarche occurred 1.13 years later (95% CI: 0.80-1.47) in athletes compared to nonathletes.

CONCLUSION

These findings suggest that AAM is a behaviourally modifiable trait. However, the quality of reported population-based study evidence is low and estimation of the true relationship between childhood PA and AAM is likely confounded by concomitant changes in diet and lifestyle behaviours.

Genetic variation in Wnt/β-catenin and ER signalling pathways in female and male elite dancers and its associations with low bone mineral density: a cross-section and longitudinal study

The association of genetic polymorphisms with low bone mineral density in elite athletes have not been considered previously. The present study found that bone mass phenotypes in elite and pre-elite dancers are related to genetic variants at the Wnt/β-catenin and ER pathways.

INTRODUCTION

Some athletes (e.g. gymnasts, dancers, swimmers) are at increased risk for low bone mineral density (BMD) which, if untreated, can lead to osteoporosis. To investigate the association of genetic polymorphisms in the oestrogen receptor (ER) and the Wnt/β-catenin signalling pathways with low BMD in elite and pre-elite dancers (impact sport athletes).

METHODS

The study included three phases: (1) 151 elite and pre-elite dancers were screened for the presence of low BMD and traditional osteoporosis risk factors (low body weight, menstrual disturbances, low energy availability); (2) a genetic association study was conducted in 151 elite and pre-elite dancers and age- and sex- controls; (3) serum sclerostin was measured in 101 pre-elite dancers and age- and sex-matched controls within a 3-year period.

RESULTS

Eighty dancers revealed low BMD: 56.3% had at least one traditional osteoporosis risk factor, whereas 28.6% did not display any risk factor (37.2% revealed traditional osteoporosis risk factors, but had normal BMD). Body weight, menstrual disturbances and energy availability did not fully predict bone mass acquisition. Instead, genetic polymorphisms in the ER and Wnt/β-catenin pathways were found to be risk factors for low BMD in elite dancers. Sclerostin was significantly increased in dancers compared to controls during the 3-year follow-up (p < 0.05).

CONCLUSIONS

Elite and pre-elite dancers demonstrate high prevalence of low BMD, which is likely related to genetic variants at the Wnt/β-catenin and ER pathways and not to factors usually associated with BMD in athletes (body weight, menstrual disturbances, energy deficiency).

Menstrual irregularity and use of oral contraceptives in female adolescent athletes in Swedish National Sports High Schools

Objective Female adolescent athletes seem to use oral contraceptives (OCs) in the same proportion as the general population. In athletes not using OCs, menstrual irregularity (MI) is reported to be common but there are few studies of MI in adolescent athletes. The aim of the study was to survey menarche, menstrual irregularity and use of OCs in adolescent athletes in the National Sports High Schools in Sweden. A further aim was to study the associations between current sport injury and menstrual irregularity as well as use of OCs. Subjects Two hundred and ninety-eight female adolescent athletes at Swedish National Sports High Schools. Methods A web-based questionnaire containing questions related to menstrual status, contraception and current injury. Results One third (32.6%) of the athletes used OCs and of the remaining athletes 31.8% had MI. The group of athletes with MI had a significantly (p = 0.038; Cohen's d, 0.32) lower BMI and consisted of a significantly (p = 0.043) higher proportion of endurance athletes. OC users were less likely to participate in endurance sports compared to non-OC users (p = 0.024). Current injury was equally distributed in the OC and the non-OC group but athletes with MI had fewer sports injuries compared to eumenorrheic women. Conclusion OCs are frequently used among athletes at Swedish National Sports High Schools. OC users were less likely to participate in endurance sports compared to non-OC users. MI was common and athletes with MI had lower BMI compared to eumenorrheic athletes. Sports injuries were not associated with use of OC and eumenorrheic athletes had a higher proportion of current injury.

Bone mass of female dance students prior to professional dance training: A cross-sectional study

Background

Professional dancers are at risk of developing low bone mineral density (BMD). However, whether low BMD phenotypes already exist in pre-vocational dance students is relatively unknown.

Aim

To cross-sectionally assess bone mass parameters in female dance students selected for professional dance training (first year vocational dance students) in relation to aged- and sex-matched controls.

Methods

34 female selected for professional dance training (10.9yrs ±0.7) and 30 controls (11.1yrs ±0.5) were examined. Anthropometry, pubertal development (Tanner) and dietary data (3-day food diary) were recorded. BMD and bone mineral content (BMC) at forearm, femur neck (FN) and lumbar spine (LS) were assessed using Dual-Energy X-Ray Absorptiometry. Volumetric densities were estimated by calculating bone mineral apparent density (BMAD).

Results

Dancers were mainly at Tanner pubertal stage I (vs. stage IV in controls, p<0.001), and demonstrated significantly lower body weight (p<0.001) and height (p<0.01) than controls. Calorie intake was not different between groups, but calcium intake was significantly greater in dancers (p<0.05). Dancers revealed a significantly lower BMC and BMD values at all anatomical sites (p<0.001), and significantly lower BMAD values at the LS and FN (p<0.001). When adjusted for covariates (body weight, height, pubertal development and calcium intake), dance students continued to display a significantly lower BMD and BMAD at the FN (p<0.05; p<0.001) at the forearm (p<0.01).

Conclusion

Before undergoing professional dance training, first year vocational dance students demonstrated inferior bone mass compared to controls. Longitudinal models are required to assess how bone health-status changes with time throughout professional training.

[Intensive training and menstrual disorders in young female: Impact on bone mass]

Participation in recreational physical activity is widely acknowledged to provide significant health benefits. Conversely, intense training imposes several constraints, such as intermittent or chronic metabolic and psychogenic training stressors and maintenance of very low body fat to maximize performance. Adolescent and adult athletic women are therefore at risk of overtraining and/or poor dietary intake, which may have several consequences for endocrine function particularly on hypothalamic-pituitary-gonadal axis. Female athletes, particularly those participating in sports needing leanness or low body weight, present a high prevalence of menstrual disorders with clinical manifestations ranging from delayed menarche, oligomenorrhea to primary and secondary amenorrhea. A high degree of variability according to the type of sport and the intensity of the practice is however observed. Exercise-related reproductive dysfunction may have some consequences for growth velocity and peak bone mass acquisition during adolescence and bone pathologies in adults. Recent findings highlight the endocrine role of adipose tissue and energy balance in the regulation of homeostasis and reproductive function. A better understanding of the mechanisms whereby intense training affects the endocrine systems may orient research to develop innovative strategies probably based on individualized nutritional approach to improve the medical care of these female athletes and protect their reproductive function.

Prevalence of low bone mineral density in female dancers

BACKGROUND AND OBJECTIVE

While some authors report that dancers have reduced bone mineral density (BMD) and increased risk of osteoporosis, others have stressed the positive effects of dance training on developing healthy BMD. Given the existing controversy, the aim of this systematic review was to examine the best evidence-based information available in relation to female dancers.

METHODS

Four databases (Web of Science, PubMed, EBSCO, Scopus) and two dance science journals (Journal of Dance Medicine and Science and Medical Problems of Performing Artists) were searched for relevant material using the keywords "dance", "ballet", "BMD", "bone density", "osteoporosis" and "female athlete triad syndrome". A total of 257 abstracts were screened using selected inclusion (studies involving bone measurements in dancers) and exclusion (editorials, opinion papers, chapters in books, narrative reviews and non-English language papers) criteria according to PRISMA guidelines. Following the above screening, a total of 108 abstracts were identified as potentially relevant. After the exclusion of conference proceedings, review papers, studies focusing only in male dancers and studies in which dancers' information were combined with other athletes, the eligible papers were subsequently assessed using the GRADE system and grouped according to: (1) prevalence of low BMD and associated factors, (2) incidence of low BMD and risk factors, (3) prevention/treatment of low BMD in dancers, and (4) other studies.

RESULTS

Of the 257 abstracts that were initially screened, only 35 studies were finally considered. Only one of these 35 was of high quality, while the remaining 34 were of relatively low quality. Seven studies reported prevalence of low BMD and associated factors, 10 reported associated factors with no prevalence data, while one reported prevalence with no associated factors data. One study cited risk factors, while another one elaborated on the treatment of low BMD in dancers. The remaining 15 studies were classified as "other studies".

CONCLUSIONS

It remains unclear whether low BMD is prevalent in female dancers. The present review highlights the need for high-quality BMD research in this area.

Endocrine disorders in adolescent and young female athletes: impact on growth, menstrual cycles, and bone mass acquisition

CONTEXT

Puberty is a crucial period of dramatic hormonal changes, accelerated growth, attainment of reproductive capacity, and acquisition of peak bone mass. Participation in recreational physical activity is widely acknowledged to provide significant health benefits in this period. Conversely, intense training imposes several constraints, such as training stress and maintenance of very low body fat to maximize performance. Adolescent female athletes are therefore at risk of overtraining and/or poor dietary intake, which may have several consequences for endocrine function. The "adaptive" changes in the hypothalamic-pituitary-gonadal, -adrenal, and somatotropic axes and the secretory role of the adipose tissue are reviewed, as are their effects on growth, menstrual cycles, and bone mass acquisition.

DESIGN

A systematic search on Medline between 1990 and 2013 was conducted using the following terms: "intense training," "physical activity," or "exercise" combined with "hormone," "endocrine," and "girls," "women," or "elite female athletes." All articles reporting on the endocrine changes related to intense training and their potential implications for growth, menstrual cycles, and bone mass acquisition were considered.

RESULTS AND CONCLUSION

Young female athletes present a high prevalence of menstrual disorders, including delayed menarche, oligomenorrhea, and amenorrhea, characterized by a high degree of variability according to the type of sport. Exercise-related reproductive dysfunction may have consequences for growth velocity and peak bone mass acquisition. Recent findings highlight the endocrine role of adipose tissue and energy balance in the regulation of homeostasis and reproductive function. A better understanding of the mechanisms whereby intense training affects the endocrine system may orient research to develop innovative strategies (ie, based on nutritional or pharmacological approaches and individualized modalities of training and competition) to improve the medical care of these adolescents and protect their reproductive function.

Nongenetic determinants of age at menarche: a systematic review

BACKGROUND

The acceleration of pubertal development is an important medical and social problem, as it may result in increased morbidity and mortality in later life. This systematic review summarizes relevant data about nongenetic factors, which contribute to age at menarche (AAM), and suggests those which may be the most important.

METHODS

The available literature from 1980 till July 2013 was searched using PubMed and Google Scholar databases. Finally, 154 papers were selected for the analysis.

RESULTS

Environmental factors, which may affect AAM, vary in populations of different ethnicity. The prenatal, infancy, and early childhood periods are the most susceptible to these factors. Body weight, high animal protein intake, family stressors (e.g., single parenting), and physical activity seem to influence AAM in most populations.

CONCLUSIONS

The data about influence of nongenetic factors on AAM are still inconsistent. The factors affecting prenatal and early childhood growth seem to have a larger effect on further sexual maturation. Further studies are needed in order to validate the association between other environmental determinants and AAM in different ethnical groups.

Effects of honey supplementation combined with different jumping exercise intensities on bone mass, serum bone metabolism markers and gonadotropins in female rats

Background

The effects of high and low jumping exercise intensities combined with honey on bone and gonadotrophins were investigated in eighty four 9 week-old female rats.

Methods

The experimental groups were 20 or 80 jumps per day combined with or without honey supplementation (HJ_20, HJ₈₀, J₂₀ and J₈₀), honey supplementation (H), sedentary without supplementation control (C), and baseline control (C₀) groups.

Results

Study results showed that HJ₈₀ elicited greatest beneficial effects on tibial and femoral mass, serum total calcium and alkaline phosphatase concentrations. There were significantly (p < 0.05) lower levels of serum follicle stimulating hormone concentrations in H, J₂₀, J₈₀ compared to C, with exception of HJ₂₀ and HJ₈₀. Serum luteinizing hormone concentrations were significantly (p < 0.05) greater in HJ₂₀, HJ₈₀ and J₂₀ compared to J₈₀.

Conclusions

It appears that high intensity jumping exercise combined with honey supplementation resulted more discernable effects on bone. Meanwhile, honey may protect against the adverse effects induced by jumping exercise on gonadotropins in female rats.

Stress hormone and reproductive system in response to honey supplementation combined with different jumping exercise intensities in female rats

This study was performed to determine the effects of 8-week honey supplementation combined with different jumping exercise intensities on serum cortisol, progesterone, estradiol, and reproductive organs. Eighty-four 9-week-old female rats were divided into 7 groups: baseline controls (C0), sedentary group (C), 20 and 80 jumps per day (Ex(20J), Ex(80J)), honey (H), and combined honey with 20 and 80 jumps per day (HEx(20J), HEx(80J)) groups. Jumping exercise was performed at 5 days/week and honey was given at a dosage of 1 g/kg body weight/day for 7 days/week. The level of serum cortisol was higher in Ex(20J) and Ex(80J) compared to C. There was significantly lower value of serum cortisol in HEx(20J) compared to Ex(80J). Serum progesterone levels were significantly lower in Ex(20J) and Ex(80J) compared to C. However, serum progesterone levels were significantly higher in HEx(20J) and HEx(80J) compared to Ex(20J) and Ex(80J). Relative uterine weights were significantly greater in HEx(20J) compared to C and HEx(80J), respectively. There was no significant difference in estradiol level and relative ovarian weights among all the groups. Therefore, honey elicited beneficial effects in reducing the increase of cortisol and in increasing the reduce of progesterone levels induced by different intensities jumping exercise in female rats.

Obstacles in the optimization of bone health outcomes in the female athlete triad

Maintaining low body weight for the sake of performance and aesthetic purposes is a common feature among young girls and women who exercise on a regular basis, including elite, college and high-school athletes, members of fitness centres, and recreational exercisers. High energy expenditure without adequate compensation in energy intake leads to an energy deficiency, which may ultimately affect reproductive function and bone health. The combination of low energy availability, menstrual disturbances and low bone mineral density is referred to as the 'female athlete triad'. Not all athletes seek medical assistance in response to the absence of menstruation for 3 or more months as some believe that long-term amenorrhoea is not harmful. Indeed, many women may not seek medical attention until they sustain a stress fracture. This review investigates current issues, controversies and strategies in the clinical management of bone health concerns related to the female athlete triad. Current recommendations focus on either increasing energy intake or decreasing energy expenditure, as this approach remains the most efficient strategy to prevent further bone health complications. However, convincing the athlete to increase energy availability can be extremely challenging. Oral contraceptive therapy seems to be a common strategy chosen by many physicians to address bone health issues in young women with amenorrhoea, although there is little evidence that this strategy improves bone mineral density in this population. Assessment of bone health itself is difficult due to the limitations of dual-energy X-ray absorptiometry (DXA) to estimate bone strength. Understanding how bone strength is affected by low energy availability, weight gain and resumption of menses requires further investigations using 3-dimensional bone imaging techniques in order to improve the clinical management of the female athlete triad.

Injury prevention for modern dancers: a pilot study of an educational intervention

Modern dancers suffer a high rate of musculoskeletal injuries. Preventing injury prolongs dance careers and eases financial burden on both individual dancers and dance companies alike. A medical student partnered with Garth Fagan Dance to develop a curriculum to teach principles of injury prevention specific to preprofessional and professional modern dancers. Quantitative assessments showed a significant increase in participant injury prevention knowledge after completion of the course (P < 0.0001). Participants' concern that injury may end their careers showed no significant change after the course (P = 0.35). Injury prevention and dance-related injuries were reported the most often as useful topics while weight management was reported the least often as a useful topic. Qualitative evaluations showed that participants' found a course on injury prevention valuable and desired a course of longer duration that includes a greater number of topics. These findings show that modern dancers perceive an educational course on injury prevention as valuable and retain information presented in the course in the short-term. Further study is warranted to assess changes in injury rates after the course and to continue to improve curriculum content and implementation.

Hypothalamic suppression during adolescence varies by bone envelope

PURPOSE

The purposes of this study were to suppress estradiol levels in adolescent (postpubertal rats) using gonadotropin-releasing hormone antagonist (GnRH-a) injections and to determine the changes in bone structure and mechanical strength.

METHODS

In an Institutional Animal Care and Use Committee-approved study, female rats at 23 d of age were assigned to a baseline group (BL65; n = 10) sacrificed on day 65, a control group (Control; n = 15) sacrificed on day 90, or an experimental group (AMEN; n = 9) sacrificed on day 90 that received daily injections of GnRH-a for a 25-d period from 65 to 90 d of age (2.5 mg·kg(-1) per dose).

RESULTS

Body weights were similar on day 65; however, the AMEN group was significantly heavier than the Control group (17%, P = 0.001) on day 90. In the AMEN rats relative to the Control group, plasma estradiol levels were reduced by 36% (P = 0.0001) and plasma insulin-like growth factor 1 levels were 24% higher (P = 0.003). In the femur, there was no change in periosteal bone apposition or total cross-sectional area. The marrow area increased by 13.7% (P = 0.05) resulting in a 7.8% decrease in relative cortical area (P = 0.012), and endocortical bone formation rate increased by 39.4% (P = 0.04). Trabecular volume and number decreased by 51.5% (P = 0.0003) and 49.5% (P = 0.0003), respectively. The absolute peak moments of the tibiae and femurs were unchanged in the AMEN group relative to the Control group, but these were reduced by 8.8% (P = 0.03) and 7.5% (P = 0.09), respectively, when normalized by body weight.

CONCLUSIONS

Suppression of estradiol by 25 d of GnRH-a administration to 65-d-old (postpubertal) rats reduced trabecular volume and number by about 50%, increased endocortical bone turnover, and reduced relative cortical thickness without changing tibial and femoral total area. These changes in bone structure were associated with no change in absolute mechanical strength possibly because of increases in body weight or in insulin-like growth factor 1 concentrations.

The influence of dance training on growth and maturation of young females: A mixed longitudinal study

BACKGROUND

The effects of systematic sports training during childhood and adolescence on subsequent growth and sexual maturation remains in dispute.

AIM

The study aimed to determine whether moderate-high volumes of dance training adversely influence linear growth and sexual maturation of young girls progressing through puberty.

SUBJECTS AND METHODS

This 3-year mixed longitudinal study comprised 82 novice dancers and 61 controls, aged 8-11 years at baseline, who were assessed bi-annually for 3 consecutive years. A biological maturational age was determined by estimating attainment of age at peak height velocity (PHV). Body dimensions were measured by anthropometry, and exercise levels, nutritional intake and age at menarche by questionnaires.

RESULTS

Controls had significantly greater unadjusted height velocity than dancers 1 year before PHV, however there was no difference between groups in age of attainment of PHV. When controlling for maturation, lean mass, fat mass and extracurricular sport (excluding dancing), there were no group differences in absolute growth or velocity of growth in height, sitting height or leg length. Within the dancers there were no effects of years of dancing (>6.5 years) or weekly dance hours (>7 h per week) on growth velocities. No association was found between age at menarche and years or hours of dance training.

CONCLUSION

Results suggest that moderate-high levels of dance training do not affect linear growth and maturation. Thus, girls should not be discouraged from dance participation on the basis of potential growth delays.

Delayed pubertal development by hypothalamic suppression causes an increase in periosteal modeling but a reduction in bone strength in growing female rats

The timing of the pubertal growth is a critical event in skeletal development. A delay in the onset of puberty has been correlated with increased stress fracture incidence in young women and as a result, suboptimal skeletal development may affect long-term bone strength. Gonadotropin releasing hormone antagonist (GnRH-a) injections were used to delay the onset of puberty in growing female rats. 23-day-old female rats were injected with a GnRH-antagonist at 2 dosage levels (n=15/group). The Low Dose group (1.25 mg/kg/dose) received daily injections for 27 days (sacrifice 49 days). The High Dose group received (5.0 mg/kg/dose) only 5 days per week over a 26 day period (sacrifice 48 days). Calcein injections measured bone formation activity on the periosteal and endocortical surfaces. Standard histomorphometric and biomechanical analyses were performed on the femora and ash content was measured on the tibiae of all animals. Serum estradiol and insulin-like growth factor (IGF)-1 levels were assayed. Significant delays in pubertal development occurred in the two GnRH-a groups as evidenced by delayed vaginal openings, decreased uterine and ovarian weights and suppressed estradiol levels compared to control. Femoral lengths were significantly shorter in the experimental groups and serum IGF-1 levels were higher than control. Bone strength and stiffness were significantly lower in the GnRH-a groups. Cortical bone area was decreased and total area was not different between groups. There was a significant decrease in % Ct.Ar/T.Ar. The decreased bone strength may have resulted from a decrease in the amount and distribution of bone, however, stress and Young's modulus were also decreased. There was a different response between endocortical formation indices and periosteal formation indices to the GnRH-a protocol. Endocortical bone formation rates decreased and there was an increase in periosteal labeled surface. A dose response between bone strength and GnRH-a dosage was found. The data suggest that hypothalamic suppression during pubertal development resulted in decreased bone strength which may result in fracture development.

Strategies to reverse bone loss in women with functional hypothalamic amenorrhea: a systematic review of the literature

Functional hypothalamic amenorrhea (FHA) impairs the attainment of peak bone mass and as such can increase the risk of fractures later in life. To document available treatment strategies, we conducted a systematic review of the literature. We report that hormonal therapies have limited effectiveness in increasing bone mass, whereas increased caloric intake resulting in weight gain and/or resumption of menses is an essential strategy for restoring bone mass in women with FHA.

INTRODUCTION

Women with functional hypothalamic amenorrhea (FHA) may not achieve peak bone mass (PBM), which increases the risk of stress fractures, and may increase the risk of osteoporotic fractures in later life.

METHODS

To identify effective treatment strategies for women with FHA, we conducted a systematic review of the literature. We included randomized controlled trials (RCTs), cross-sectional studies, and case studies that reported on the effects of pharmacological and non-pharmacological interventions on bone mineral density (BMD) or bone turnover in women with FHA.

RESULTS

Most published studies (n=26) were designed to treat the hormonal abnormalities observed in women with FHA (such as low estrogen, leptin, insulin-like growth factor-1, and DHEA); however none of these treatments demonstrated consistent improvements in BMD. Therapies containing an estrogen given for 8-24 months resulted in variable improvements (1.0-19.0%) in BMD, but failed to restore bone mass to that of age-matched controls. Three studies reported on the use of bisphosphonates (3-12 months) in anorexic women, which appear to have limited effectiveness to improve BMD compared to nutritional treatments. Another three investigations showed no improvements in BMD after androgen therapy (DHEA and testosterone) in anorexic women. In contrast, reports (n=9) describing an increase in caloric intake that results in weight gain and/or the resumption of menses reported a 1.1-16.9% increase in BMD concomitant with an improvement in bone formation and reduction in bone resorption markers.

CONCLUSIONS

Our literature review indicates that the most successful, and indeed essential strategy for improving BMD in women with FHA is to increase caloric intake such that body mass is increased and there is a resumption of menses. Further long-term studies to determine the persistence of this effect and to determine the effects of this and other strategies on fracture risk are needed.

Short-term delay of puberty causes a transient reduction in bone strength in growing female rats

Multiple factors affect the structural development of the skeleton; in particular, estrogen levels during growth are an important factor in the pathogenesis of bone fragility. The delay of menarche and infrequent menstrual cycles decrease estrogen levels during adolescence and decrease peak bone mass. The aim of this study was to determine if delayed puberty through administration of a GnRH antagonist initiated prior to the onset of the first estrus cycle would delay the increase in estrogen levels and impede bone strength development in female rats. Twenty-three-day-old female Sprague-Dawley rats were randomly assigned to one of four groups; 1) short-term control group (C-ST) (n = 12), 2) long-term control (C-LT) (n = 12), 3) short-term GnRH antagonist group (G-ST) (n = 12) and 4) long-term GnRH antagonist group (G-LT) (n = 12). Injections (0.2 ml) of either saline or GnRH antagonist (100 microg/day) (Cetrotide, Serono, Inc) were given intraperitoneally for a duration of 18 days. Pubertal and gonadal development was retarded as indicated by a delay in vaginal opening (an indicator of pubertal onset), lower ovarian and uterine weights and lower estradiol levels in the short-term experimental animals (G-ST). However, at maturity (G-LT), there were no significant differences found in these measures. A delay in the timing of puberty significantly attenuated the development of femoral bone strength at 6 weeks of age. Peak moment, yield moment and stiffness in the G-ST group were all significantly less than the C-ST group. Cortical width was significantly attenuated due to the increased percentage of marrow area per total bone area in the G-ST group. However, femoral bone strength was recovered at maturity (G-LT). In summary, a transient delay in pubertal timing has short-term effects on bone strength development. In the current animal model of delaying puberty through GnRH antagonist injections, there appears to be no long-term effects on bone strength.

Influence of high-intensity training and of dietetic and anthropometric factors on menstrual cycle disorders in ballet dancers

Background. Intensity of exercise and low energy consumption, specific type and amount of training, early age at initiation, previous menstrual dysfunctions, low body mass index (BMI) or percentage body fat, pathological feeding habits and psychological stress have been suggested as potential factors accountable for menstrual irregularities in female athletes.Aim. To evaluate the influence of intensive training and of dietetic and anthropometric factors on menstrual cycles in female ballet dancers.Method. A case-control study, in which a structured interview and physical examination were carried out in two groups of teenagers aged between 12 and 18 years. The study included a total of 115 adolescent girls distributed in two groups: dancers (group B, n = 38) and girls of the same age not engaged in any sports activity (group C, n = 77).Results. Early starting high-intensity training delayed the onset of menarche ( p < 0.001). Dancers had a higher prevalence of oligomenorrhea and amenorrhea than control girls ( p = 0.004). Additionally, the dancers had lower scores in anthropometric variables: breast circumference 80 cm vs. 86.6 cm for controls ( p = 0.0001), low weight in 18% of dancers vs. 2.6% of controls ( p = 0.0001), and low height in 18% of dancers vs. 9% of controls ( p = 0.016). In addition, in dancers, low BMI was observed in 21% compared with 13% of controls ( p = 0.0001). Finally, 32% of the dancers were on a weight-control diet while this percentage decreased to 12% for the girls in control group (odds ratio = 3.49, 95% confidence interval = 1.31-9.25).Conclusions. In ballet dancers, high-intensity training was associated with late onset of menarche, menstrual disorders, lower weight and height development, and abnormal feeding behaviors.

Older women track and field athletes have enhanced calcaneal stiffness

Vigorous weight-bearing exercise is recommended to women as a method of osteoporosis prevention. This study examined older women athletes to see if they indeed were less likely to develop osteoporosis than those in the general population, and to investigate which factors could have contributed to these results. One hundred and thirty-nine women 40-88 years old, all competitors in a USA National Masters Track and Field Championships, volunteered for the study. Masters refers to competitors > or =40 years old. Their calcaneal stiffness (SI) was measured by a Lunar Achilles+ ultrasonometer. Subjects were also measured for height and weight, and completed a questionnaire on exercise history, diet, lifestyle factors, medical and menopausal issues, and use of hormone replacement therapy (HRT). The women, mean age 57.3 years, had an overall average SI of 99.5 (T-score = 0.04) which is equivalent to that of a 20-year-old woman and 20.8% higher than expected for women of their age. Their median SI remained not different from expected peak bone SI until the age of 70. For analysis, this cohort of women was divided into two groups: premenopausal and postmenopausal athletes. The SI of both groups was correlated with the earliest age at which they had first participated in sports or exercises that impart moderate to high strain rates to the lower limbs and with current participation in high impact track and field events. Variables correlated with SI in the general population, such as weight, HRT, previous fracture, hysterectomy, and current menopausal status, did not predict SI in this cohort. In conclusion, women competing in Masters track and field at the national level had calcaneal stiffness substantially higher than expected for women of their age in the general population, and their participation in vigorous sports and activities, either currently or at a younger age, was predictive of this association.

The Dancer as a Performing Athlete

The physical demands placed on dancers from current choreography and performance schedules make their physiology and fitness just as important as skill development. However, even at the height of their professional careers, dancers' aerobic power, muscular strength, muscular balance, bone and joint integrity are the 'Achilles heels' of the dance-only selection and training system. This partly reflects the unfounded view, shared by sections of the dance world, that any exercise training that is not directly related to dance would diminish dancers' aesthetic appearances. Given that performing dance itself elicits only limited stimuli for positive fitness adaptations, it is not surprising that professional dancers often demonstrate values similar to those obtained from healthy sedentary individuals of comparable age in key fitness-related parameters. In contrast, recent data on male and female dancers revealed that supplementary exercise training can lead to improvements of such fitness parameters and reduce incidents of dance injuries, without interfering with key artistic and aesthetic requirements. It seems, however, that strict selection and training regimens have succeeded in transforming dance to an activity practised by individuals who have selectively developed different flexibility characteristics compared with athletes. Bodyweight targets are normally met by low energy intakes, with female dance students and professional ballerinas reported to consume below 70% and 80% of the recommended daily allowance of energy intake, respectively, while the female athlete 'triad' of disordered eating, amenorrhoea and osteoporosis is now well recognised and is seen just as commonly in dancers. An awareness of these factors will assist dancers and their teachers to improve training techniques, to employ effective injury prevention strategies and to determine better physical conditioning. However, any change in the traditional training regimes must be approached cautiously to ensure that the aesthetic content of the dance is not affected by new training techniques. Since physiological aspects of performing dance have been viewed primarily in the context of ballet, further scientific research on all forms of dance is required.

Influence of dietetic and anthropometric factors and of the type of sport practised on bone density in different groups of women

OBJECTIVE

The aim of this work was to analyse the influence of dietetic and anthropometric data, as well as the sport practised, on the bone density of different groups of sportswomen.

SUBJECTS AND METHODS

Dietetic, anthropometric and bone density data were collected from 74 women who practised different sports (15 skiers, 26 basketball players and 33 ballet dancers), and compared to those of 90 women who led sedentary lifestyles.

RESULTS

The sportswomen had higher bone mineral contents and bone densities than controls. However, the dancers showed similar spinal and hip values as those of controls, and lower forearm values. Low body weight and body mass index, and insufficient energy intake-characteristic of the dancers-were associated with poorer bone mineralisation status. Increased energy, protein, vitamin D, calcium, zinc and magnesium intakes were associated with greater bone density and mineral content at different sites.

CONCLUSIONS

The worst bone density status was that of the dancers, who, as a group, displayed characteristics that have negative impacts in this respect (low energy intakes and low body weight). Dancers should therefore take steps to avoid suffering fractures and skeleto-muscular lesions which could negatively influence their health and physical performance. The greater consumption of milk products and calcium and better Ca/P ratio seen in the dancers could help this group to avoid bone deterioration.